Conway's Game of Life in J

I thought I'd give J (link) a try and implemented Conway's Game of Life in it.

Code:
(]+.&(3&=)+)+/((4&{.,(_4&{.))(>,{,~<i:1))&|.

Sample:
   f =: 5 5 $ 0 1 0 0 0   0 0 1 0 0   1 1 1 0 0   0 0 0 0 0    0 0 0 0 0
   f
0 1 0 0 0
0 0 1 0 0
1 1 1 0 0
0 0 0 0 0
0 0 0 0 0
   f (]+.&(3&=)+)+/((4&{.,(_4&{.))(>,{,~<i:1))&|. f
0 0 0 0 0
1 0 1 0 0
0 1 1 0 0
0 1 0 0 0
0 0 0 0 0